I've read a lot about different programs and such but haven't come across much on when to start formal training.We are letting our 3 m/o be a pup and incorporating some basic commands along with crate and house breaking.

But when "should" the rubber meet the road and we regiment this thing?

In the military we start close to 8-12 months of age for the serious work to begin. Everything leading up to 8months should be the most important part,OB. Now for whatever you plan on doing is on you and your particular dog. I just hope you got your money's worth on the dog /breed you wanted. Can't tell you numbers but trust me we have a lot that wash out. They ain't cheap neither. We'll, I'm sure I didn't help much but hope I gave something.

Define "formal". For me, I consider a pup a "recruit" and his / her training starts with me the moment they become mine. Pups have an incredible amount to learn on their way to becoming competent gundogs. The journey I take with a pup is a cyclical one, not a linear one. I continually work on new concepts and embedding those behaviors, while making certain to revisit those previously worked on and further reinforcing those behaviors desired.